/*!\file  list.h  Modified Linux Kernel list implementation.
 *
 *      This file is part of the micro-rtos package.
 *
 *  Copyright (c)
		Linux Kernel Developers <www.kernel.org>
		'Tutorial' by Gabriel Zabusek <gabriel.zabusek@gmail.com>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#ifndef LIST_H
#define LIST_H

/*
 *
 * This is pretty much a one to one copy of the Linux Kernel list
 * except that some of the features were disabled so no additional
 * header files have to be included.
 *
 * Usage:
 *
 * declare your structure - list node - containing list_head at first:
 * struct my_list_t {
 * 	int nValueA;
 * 	int nValueB;
 *
 * 	struct list_head list;
 * };
 *
 * ...
 *
 * - initialize your list head first:
 *
 * struct my_list_t my_list;
 * INIT_LIST_HEAD(&my_list.list);
 *
 * - inserting new items to the list:
 *
 * for(int i=0; i<10; i++){
 * 	//allocate the memory;
 *	struct my_list_t * new_item = (struct my_list_t *)malloc( sizeof( struct my_list_t ) );
 *
 * 	//initialize the new item - fill it with values etc.
 *	new_item->nValueA = i;
 *	new_item->nValueB = (i-1)*2*PI;
 *
 * 	//add to the list
 *	list_add( &(new_item->list), &(my_list->list) );
 *
 *	//Note: you can also use list_add_tail to add to the tail of the list
 *}
 *
 * - going through the list - use macro list_for_each or list_for_each_entry
 *
 * //Note: using list_for_each_entry makes things a lot (1 line :-) ) easier
 * 
 * //declare a iterator
 * struct my_list_t * iterator; 
 * list_for_each_entry(iterator, &my_list.list, list){ //enter the for each cycle
 * 	//do something with the current node to which iterator is pointing to
 * 	printf("Value A:%d, Value B:%d",iterator->nValueA, iterator->nValueB);
 * }
 *
 * // -- list_for_each usage example
 *
 * //declare a iterator first
 * struct list_head * iterator;
 * list_for_each( iterator, &my_list.list ){ //start for each cycle
 * 	
 *	//get the whole structure iterator is pointing to at the moment 
 *	//using the list_entry function
 * 	struct my_list_t * tmp_node = list_entry( iterator, struct my_list_t, list );
 *
 * 	printf("Value A: %d, Value B: %d", tmp_node->nValueA, tmp_node->nValueB
 * }
 *
 * //NOTE: if you plan on deleting some items while in the cycle use list_for_each_safe
 * //      macro instead -> the reason is obvious.
 *
 * - deleting all items in one cycle
 *
 *   struct list_head *it, *tmp;
 *   list_for_each_safe( it, tmp, &my_list.list ){
 *   	struct my_list_t * current = list_entry( it, struct my_list_t, list );
 *
 *	//delete current item from the list
 *	list_del( it );
 *
 *	//and free its memory
 *	free( it );
 *   }
 *
 *
 *
 * Thanks to Linux Kernel Developers for such a cool version of list
 * Gabriel Zabusek
 *
 * */


/*
 * Simple doubly linked list implementation.
 *
 * Some of the internal functions ("__xxx") are useful when
 * manipulating whole lists rather than single entries, as
 * sometimes we already know the next/prev entries and we can
 * generate better code by using them directly rather than
 * using the generic single-entry routines.
 */

typedef struct list_head {
	struct list_head *next, *prev;
} list_node;


static inline void INIT_LIST_HEAD (struct list_head *list)
{
        list->next = list;
        list->prev = list;
}

/*
 * Insert a new entry between two known consecutive entries. 
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_add(struct list_head *new,
			      struct list_head *prev,
			      struct list_head *next)
{
	next->prev = new;
	new->next = next;
	new->prev = prev;
	prev->next = new;
}

/**
 * list_add - add a new entry
 * @new: new entry to be added
 * @head: list head to add it after
 *
 * Insert a new entry after the specified head.
 * This is good for implementing stacks.
 */
static inline void list_add(struct list_head *new, struct list_head *head)
{
	__list_add(new, head, head->next);
}

/**
 * list_add_tail - add a new entry
 * @new: new entry to be added
 * @head: list head to add it before
 *
 * Insert a new entry before the specified head.
 * This is useful for implementing queues.
 */
static inline void list_add_tail(struct list_head *new, struct list_head *head)
{
	__list_add(new, head->prev, head);
}

/*
 * Delete a list entry by making the prev/next entries
 * point to each other.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_del(struct list_head *prev, struct list_head *next)
{
	next->prev = prev;
	prev->next = next;
}

/**
 * list_del - deletes entry from list.
 * @entry: the element to delete from the list.
 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
 */
static inline void list_del(struct list_head *entry)
{
	__list_del(entry->prev, entry->next);
	entry->next = (void *) 0;
	entry->prev = (void *) 0;
}

/**
 * list_del_init - deletes entry from list and reinitialize it.
 * @entry: the element to delete from the list.
 */
static inline void list_del_init(struct list_head *entry)
{
	__list_del(entry->prev, entry->next);
	INIT_LIST_HEAD(entry); 
}

/**
 * list_move - delete from one list and add as another's head
 * @list: the entry to move
 * @head: the head that will precede our entry
 */
static inline void list_move(struct list_head *list, struct list_head *head)
{
        __list_del(list->prev, list->next);
        list_add(list, head);
}

/**
 * list_move_tail - delete from one list and add as another's tail
 * @list: the entry to move
 * @head: the head that will follow our entry
 */
static inline void list_move_tail(struct list_head *list,
				  struct list_head *head)
{
        __list_del(list->prev, list->next);
        list_add_tail(list, head);
}

/**
 * list_empty - tests whether a list is empty
 * @head: the list to test.
 */
static inline int list_empty(struct list_head *head)
{
	return head->next == head;
}

static inline void __list_splice(struct list_head *list,
				 struct list_head *head)
{
	struct list_head *first = list->next;
	struct list_head *last = list->prev;
	struct list_head *at = head->next;

	first->prev = head;
	head->next = first;

	last->next = at;
	at->prev = last;
}

/**
 * list_splice - join two lists
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 */
static inline void list_splice(struct list_head *list, struct list_head *head)
{
	if (!list_empty(list))
		__list_splice(list, head);
}

/**
 * list_splice_init - join two lists and reinitialise the emptied list.
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 *
 * The list at @list is reinitialised
 */
static inline void list_splice_init(struct list_head *list,
				    struct list_head *head)
{
	if (!list_empty(list)) {
		__list_splice(list, head);
		INIT_LIST_HEAD(list);
	}
}

/**
 * list_entry - get the struct for this entry
 * @ptr:	the &struct list_head pointer.
 * @type:	the type of the struct this is embedded in.
 * @member:	the name of the list_struct within the struct.
 */
#define list_entry(ptr, type, member) \
	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**
 * list_for_each	-	iterate over a list
 * @pos:	the &struct list_head to use as a loop counter.
 * @head:	the head for your list.
 */
#define list_for_each(pos, head) \
	for (pos = (head)->next; pos != (head); \
        	pos = pos->next)
/**
 * list_for_each_prev	-	iterate over a list backwards
 * @pos:	the &struct list_head to use as a loop counter.
 * @head:	the head for your list.
 */
#define list_for_each_prev(pos, head) \
	for (pos = (head)->prev; pos != (head); \
        	pos = pos->prev)
        	
/**
 * list_for_each_safe	-	iterate over a list safe against removal of list entry
 * @pos:	the &struct list_head to use as a loop counter.
 * @n:		another &struct list_head to use as temporary storage
 * @head:	the head for your list.
 */
#define list_for_each_safe(pos, n, head) \
	for (pos = (head)->next, n = pos->next; pos != (head); \
		pos = n, n = pos->next)

/**
 * list_for_each_entry	-	iterate over list of given type
 * @pos:	the type * to use as a loop counter.
 * @head:	the head for your list.
 * @member:	the name of the list_struct within the struct.
 */
#define list_for_each_entry(pos, head, member)				\
	for (pos = list_entry((head)->next, typeof(*pos), member);	\
	     &pos->member != (head); 					\
	     pos = list_entry(pos->member.next, typeof(*pos), member))

/**
 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 * @pos:	the type * to use as a loop counter.
 * @n:		another type * to use as temporary storage
 * @head:	the head for your list.
 * @member:	the name of the list_struct within the struct.
 */
#define list_for_each_entry_safe(pos, n, head, member)			\
	for (pos = list_entry((head)->next, typeof(*pos), member),	\
		n = list_entry(pos->member.next, typeof(*pos), member);	\
	     &pos->member != (head); 					\
	     pos = n, n = list_entry(n->member.next, typeof(*n), member))

static inline unsigned int list_size(struct list_head * head){
	struct list_head * iterator;
	unsigned int size = 0;
	list_for_each(iterator, head){
		size++;	
	}
	return size;
}

#endif
